[Eeglablist] Source localization and hippocanpus

[Philip Zeman]

Hi Eugen,

in my own past work I found sources (expected) in hippocampal/temporal
regions. The ICA and volume localization I used implicated parts parts of
the temporal lobe together with the hippocampus.

I'm glad you're looking into this.

Philip

On Thu, Jan 15, 2026 at 5:24 AM Евгений Машеров via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Using source localization methods, we were able to find foci located in
> the hippocampus. These were confirmed during surgery. This is difficult to
> explain from the standpoint of pure dipole theory, and is one of the
> motivations for me to develop a method that takes into account non-dipole
> sources. The field they generate may weaken with increasing distance less
> dramatically than that of a dipole, and the task of reconstructing the
> signal from deep sources may not be so hopeless.
>
> Eugen Masherov
>
> > We made a good case that the Feedback Negativity (FN) originates from
> > the striatum (Foti, Weinber, Dien, & Hajcak, 2011, 2011). It's not a
> > claim to be made lightly. The cortex is a strong candidate as far-field
> > generators because it is rich on pyramidal neurons, which have
> > asymmetrical dendrites and tend to be oriented in the same direction,
> > but that does not mean it is the only possible source. To make a case
> > for a subcortical generator, you have to be able to demonstrate
> > convergent validity with data from methods like intracranial EEG
> > recordings. See our papers for arguments and references.
> >
> > The hippocampus, on the other hand, is the classic example of a
> > structure that is likely to be a closed field generator because it is in
> > the form of a tube, wherein the field from a given neuron is likely to
> > be canceled out by the field from a neuron pointing the opposite
> > direction on the other side of the tube, resulting in a net zero voltage
> > field when measured from outside the tube. No amount of electrodes or
> > computational sophistication is going to help with that. Of course,
> > it's all complicated because the entire tube isn't necessarily equally
> > active. Also, the adjoining parahippocampal cortex isn't a tube. There
> > seems to be a lot of discussion going on right now about what can be
> > measured. But yeah, making a plausible claim for a hippocampal
> > generator would require very strong evidence. As John says, it's easy
> > to put a equivalent dipole in the hippocampal region and get non-zero
> > results, so not strong evidence by itself. But I'd also be wary of
> > making sweeping generalizations.
> >
> > Joe
> >
> > Foti, D., Weinberg, A., Dien, J., & Hajcak, G. (2011). Event-related
> > potential activity in the basal ganglia differentiates rewards from
> > nonrewards: Temporospatial principal components analysis and source
> > localization of the feedback negativity. /Hum Brain Mapp/, /32/(12),
> > 2207–2216.
> https://urldefense.com/v3/__https://doi.org/10.1002/hbm.21182__;!!Mih3wA!F6lfB756tGdH_QFKwL5mIWetNG672s_aafnqgyt9T8wO7nrcuWuqfT_GvDz4sGND_j85H6f_kjzDtWSplqI$
> >
> > Foti, D., Weinberg, A., Dien, J., & Hajcak, G. (2011). Event-related
> > potential activity in the basal ganglia differentiates rewards from
> > nonrewards: Response to commentary. /Hum Brain Mapp/, /32/(12),
> > 2267–2269.
> https://urldefense.com/v3/__https://doi.org/10.1002/hbm.21357__;!!Mih3wA!F6lfB756tGdH_QFKwL5mIWetNG672s_aafnqgyt9T8wO7nrcuWuqfT_GvDz4sGND_j85H6f_kjzDCIoX_BY$
> >
> > On 1/14/26 18:52, Richards, John via eeglablist wrote:
> >
> >> The hippocampus, caudate, putamen, amygdala, sometimes are classified
> with "cortex" as gray matter and people might try to do source analysis.
> However, only the cortex has the perpendicular pyramidal structure that
> conducts current to the scalp, and the "subcortical" brain areas do not
> have the correct structure to generate current on the scalp. If you put
> source locations in these areas and do source analysis you will get
> "something", likely due to activity in other brain areas, noise, or other
> non-neuron activity.
> >>
> >> I think that a couple of the "internal" cortex ROIs, like the insula,
> have the cortex structure to generate current. But its possible that it
> cannot be measured because the area is relatively far from the scalp and
> any current would be small.
> >>
> >> John
> >>
> >> ***********************************************
> >> John E. Richards
> >> Carolina Distinguished Professor
> >> Department of Psychology
> >> University of South Carolina
> >> Columbia, SC 29208
> >> Dept Phone: 803 777 2079
> >> Fax: 803 777 9558
> >> Email:richards-john at sc.edu
> >>
> https://urldefense.com/v3/__https://jerlab.sc.edu/__;!!Mih3wA!ETNTEAJ6TN4Jy-leSX_wNE4oEjcJRGEvhvPv9VUow0FLXB7TonoRBJczbLfGx7O-lhiZ8zLs-rOV6e3nqjWwi01tM5J3lQ$
> >> ***********************************************
> >>
> >> -----Original Message-----
> >> From: eeglablist<eeglablist-bounces at sccn.ucsd.edu> On Behalf Of Cedric
> Cannard via eeglablist
> >> Sent: Wednesday, January 14, 2026 3:43 PM
> >> To: EEGLAB List<eeglablist at sccn.ucsd.edu>
> >> Subject: [Eeglablist] Source localization and hippocanpus
> >>
> >> Hi everyone,
> >>
> >> My understanding is that it is impossible to reliably pick up activity
> from the hippocampus when doing any form of source
> localization/reconstruction from 64 channels EEG data (or more?). Is that
> still correct or are there solutions I am not aware of?
> >>
> >> Thanks,
> >>
> >> Cedric
> >>
> >> Sent from [Proton Mail](
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> > --
> >
> --------------------------------------------------------------------------------
> >
> > Joseph Dien, PhD
> > Senior Research Scientist
> > Department of Human Development and Quantitative Methodology
> > University of Maryland, College Park
> > E-mail:jdien at umd.edu
> >
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